An IP multimedia subsystem (IMS) takes a packet switched domain as an upper control signaling and a media transmission bearer channel and takes a session initial protocol (SIP) as a service control protocol to separate service control from bearer control so as to provide diversified multimedia services. An IMS network is a target network of a telecommunication core network, plays an important role in the telecommunication network, has an integration capability of converging multiple mobile and fixed access networks conveniently, and wins support from more and more telecommunication equipment manufacturers and operators.
Lawful interception means that a national security organization sets a specific intercepted object on communication equipment under the authorization of laws, and sends session event information and communication content of the specific intercepted object to an interception center designated by the security organization through a specific interface. The interception center can recover a communication event and the communication content of the intercepted object according to the information to achieve the interception purpose. The lawful interception should be also implemented in an IMS network, and IMS interception refers to anchoring a media stream of an intercepted session to a media-level net element controlled by an IMS core through a core network and intercepting the media stream of the intercepted session.
In the existing technology, a proxy-call session control function (P-CSCF) controls an access-border gateway function (A-BGF) to copy the media stream by determining a session interception mode on a call session control function (CSCF) so as to copy the communication content of the session, that is, interception of an IMS user is implemented on the A-BGF. When the P-CSCF obtains IP multimedia public identity (IMPU) information about the user which is accessed to an IMS domain through the P-CSCF, the P-CSCF judges whether the session is required to be intercepted according to the IMPU information. When the user is required to be intercepted, the P-CSCF controls the A-BGF to copy the media stream of the session to an law enforcement monitoring facility (LEMF) by a Gq′ interface between the P-CSCF and an service policy decision function (SPDF) and an Ia interface between the SPDF and the A-BGF, and the LEMF is adapted to set, maintain and control all interception events.
During implementation of the embodiment of the present invention, inventors find that the existing technology at least has the following problems:
In the existing technology, the interception process is implemented in need of the interface between the P-CSCF and the SPDF and the interface between the SPDF and the A-BGF, but the interfaces have no unified standard and are difficult for joint.